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- Apr 23, 2011
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Tarmo, I think you have missed something in GK's post
He copied the leadscrew pattern onto the gear blank and then using a small grinder, Think Dremel tool, to cut the teeth freehand.
Cheers Phil
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Is it posible to make a thread chasing dial?
- Thread starter tarmo120
- Start date
Cheers Phil
I have made a bunch of geqrs for the early South Bend Type 5 or #405 Workshop lathe.
This has a LH l;ead screw so the gear is a bit different.
Attached is my setup. This is for an 8 tpi leadscrew. The cutting tool is an ID ACME threading tool grund for 8 TPI. The blank is set at about a 6 or 7 degree andle to match the lead of the screw. The loading is light so you do not need a concave gear.
I moved the gear under the cutter so the profile is flat. If I wanted to get it complicated I could have set the tool to stick out thread rooth depth and moved the blank up and into the cutter and then down and index and then up and then down etc. But many of the SB gears were just this shape so why make it complicated.
The material is Moly filled Delrin. That stuff is designed for gears.
This has a LH l;ead screw so the gear is a bit different.
Attached is my setup. This is for an 8 tpi leadscrew. The cutting tool is an ID ACME threading tool grund for 8 TPI. The blank is set at about a 6 or 7 degree andle to match the lead of the screw. The loading is light so you do not need a concave gear.
I moved the gear under the cutter so the profile is flat. If I wanted to get it complicated I could have set the tool to stick out thread rooth depth and moved the blank up and into the cutter and then down and index and then up and then down etc. But many of the SB gears were just this shape so why make it complicated.
The material is Moly filled Delrin. That stuff is designed for gears.
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As 12bolts said, I simply got an impression therefore no math. Can be done even with white paper
remember rubbing an eraser on paper over a penny. Then I free hand cut the teeth with a cut off
wheel on a air die grinder. NOTE one thing I forgot to say is, if your leadscrew is keyed the gear
blank will have to be dished out to the diameter of the screw. Thats so it dont get stuck or jump
when the key comes around. Now If you do not have a key a proper washer will do such as like
my big lathe is twin screw meaning the threading screw is not keyed so a washer works fine.
I still need a camara battery then you will see how easy it is.
One more if keyed the gear blank will have to be fat so when the key comes around a tooth is
entering and a tooth is exiting (the keyway)
remember rubbing an eraser on paper over a penny. Then I free hand cut the teeth with a cut off
wheel on a air die grinder. NOTE one thing I forgot to say is, if your leadscrew is keyed the gear
blank will have to be dished out to the diameter of the screw. Thats so it dont get stuck or jump
when the key comes around. Now If you do not have a key a proper washer will do such as like
my big lathe is twin screw meaning the threading screw is not keyed so a washer works fine.
I still need a camara battery then you will see how easy it is.
One more if keyed the gear blank will have to be fat so when the key comes around a tooth is
entering and a tooth is exiting (the keyway)
I have a box of small medium and large gears that I accumulated while collecting machinist chests. If you can come up with specs for what kind of gear you need I can dig through it and see if anything fits. My experience is minimal so you'd have to provide a tooth count and something easy for me to measure like outer diameter or something.
Tools4Cheap is selling a replacement (reproduction) thread dial for certain southbends for $100 if that might fit the bill. I don't know the specs for your lathe or for Southbend.
Joe
Tools4Cheap is selling a replacement (reproduction) thread dial for certain southbends for $100 if that might fit the bill. I don't know the specs for your lathe or for Southbend.
Joe
- Joined
- Aug 20, 2011
- Messages
- 527
Re: Is it possible to make a thread chasing dial?
I will need to make one for my 14 1/2 inch SB ....6tpi 1 1/8 screw ....I get the part about rolling the blank to mark it , but how do you determine it's(blanks) diameter..24t =4"circumference? I know that is not the proper way to describe a gear ....but will that work??..I see a 48 tooth on the Grizzly site for the thread dial they sell (gear is $11 ) how do I determine if it will work on the 6tpi screw on my lathe??What do I ask them? I don't want to buy the whole thing ...just the gear...looks like it may be for a smaller lathe though.....this should be my first project on the 14 1/2...I will pick it up in the am ...very excited
I will need to make one for my 14 1/2 inch SB ....6tpi 1 1/8 screw ....I get the part about rolling the blank to mark it , but how do you determine it's(blanks) diameter..24t =4"circumference? I know that is not the proper way to describe a gear ....but will that work??..I see a 48 tooth on the Grizzly site for the thread dial they sell (gear is $11 ) how do I determine if it will work on the 6tpi screw on my lathe??What do I ask them? I don't want to buy the whole thing ...just the gear...looks like it may be for a smaller lathe though.....this should be my first project on the 14 1/2...I will pick it up in the am ...very excited
Last edited:
That was my question also.
Today I have made a few pictures for you to see. And help me out determing the nature of the leadscrew. Metric or not.
The outside diameter of the leadscrew is 20mm or .786 inches.
Since I couldn't figure out if it a single thread or double thread screw I'm not sure on the TPI or Pitch.
I measured from the right side of one thread to the same side on the next one.
It measured 3.0mm or .115 inches.
And on the length of 1 inch I got 9 threads.
I did go through the manual 3 times and the only thing that could point to metric leadscrew is shown in the second picture. The thread table.
And then I googled a few hours and came up with this.
If indeed I have a metric leadscrew then I think I'm not going to mess with it. Just leave it be and work with I've got.
When I do threading I'll have 99% of the time metric threads.
Today I have made a few pictures for you to see. And help me out determing the nature of the leadscrew. Metric or not.
The outside diameter of the leadscrew is 20mm or .786 inches.
Since I couldn't figure out if it a single thread or double thread screw I'm not sure on the TPI or Pitch.
I measured from the right side of one thread to the same side on the next one.
It measured 3.0mm or .115 inches.
And on the length of 1 inch I got 9 threads.
I did go through the manual 3 times and the only thing that could point to metric leadscrew is shown in the second picture. The thread table.
And then I googled a few hours and came up with this.
If indeed I have a metric leadscrew then I think I'm not going to mess with it. Just leave it be and work with I've got.
When I do threading I'll have 99% of the time metric threads.
I was googling/binging/yahooing for info on my own lathe today and came across another thread on another forum in a galaxy far far away.
http://tinyurl.com/au5hf8m
Halfway down the page are some directions and it looks like, if I'm reading correctly, that all you need to know is the pitch of your leadscrew - which you've already established at 9tpi. Based on that, any 36 tpi screw with teeth that fit between the thread of your leadscrew should do the trick.
Joe
http://tinyurl.com/au5hf8m
Halfway down the page are some directions and it looks like, if I'm reading correctly, that all you need to know is the pitch of your leadscrew - which you've already established at 9tpi. Based on that, any 36 tpi screw with teeth that fit between the thread of your leadscrew should do the trick.
Joe